<!DOCTYPE html>
<html lang="en">
<head>
    <title>three.js - misc - octree collisions</title>
    <meta charset=utf-8 />
    <meta name="viewport" content="width=device-width, user-scalable=no, minimum-scale=1.0, maximum-scale=1.0">
    <link type="text/css" rel="stylesheet" href="main.css">
</head>
<body>
<div id="info">
    Octree threejs demo - basic collisions with static triangle mesh<br />
    MOUSE to look around and to throw balls<br/>
    WASD to move and SPACE to jump
</div>
<div id="container"></div>

<!-- Import maps polyfill -->
<!-- Remove this when import maps will be widely supported -->
<script async src="https://unpkg.com/es-module-shims@1.3.6/dist/es-module-shims.js"></script>

<script type="importmap">
			{
				"imports": {
					"three": "../build/three.module.js"
				}
			}
		</script>

<script type="module">

    import * as THREE from 'three';

    import Stats from './jsm/libs/stats.module.js';

    import { GLTFLoader } from './jsm/loaders/GLTFLoader.js';

    import { Octree } from './jsm/math/Octree.js';
    import { OctreeHelper } from './jsm/helpers/OctreeHelper.js';

    import { Capsule } from './jsm/math/Capsule.js';

    import { GUI } from './jsm/libs/lil-gui.module.min.js';

    const clock = new THREE.Clock();

    const scene = new THREE.Scene();
    scene.background = new THREE.Color( 0x88ccee );
    scene.fog = new THREE.Fog( 0x88ccee, 0, 50 );

    const camera = new THREE.PerspectiveCamera( 70, window.innerWidth / window.innerHeight, 0.1, 1000 );
    camera.rotation.order = 'YXZ';

    const fillLight1 = new THREE.HemisphereLight( 0x4488bb, 0x002244, 0.5 );
    fillLight1.position.set( 2, 1, 1 );
    scene.add( fillLight1 );

    const directionalLight = new THREE.DirectionalLight( 0xffffff, 0.8 );
    directionalLight.position.set( - 5, 25, - 1 );
    directionalLight.castShadow = true;
    directionalLight.shadow.camera.near = 0.01;
    directionalLight.shadow.camera.far = 500;
    directionalLight.shadow.camera.right = 30;
    directionalLight.shadow.camera.left = - 30;
    directionalLight.shadow.camera.top	= 30;
    directionalLight.shadow.camera.bottom = - 30;
    directionalLight.shadow.mapSize.width = 1024;
    directionalLight.shadow.mapSize.height = 1024;
    directionalLight.shadow.radius = 4;
    directionalLight.shadow.bias = - 0.00006;
    scene.add( directionalLight );

    const container = document.getElementById( 'container' );

    const renderer = new THREE.WebGLRenderer( { antialias: true } );
    renderer.setPixelRatio( window.devicePixelRatio );
    renderer.setSize( window.innerWidth, window.innerHeight );
    renderer.shadowMap.enabled = true;
    renderer.shadowMap.type = THREE.VSMShadowMap;
    renderer.outputEncoding = THREE.sRGBEncoding;
    renderer.toneMapping = THREE.ACESFilmicToneMapping;
    container.appendChild( renderer.domElement );

    const stats = new Stats();
    stats.domElement.style.position = 'absolute';
    stats.domElement.style.top = '0px';
    container.appendChild( stats.domElement );

    const GRAVITY = 30;

    const NUM_SPHERES = 100;
    const SPHERE_RADIUS = 0.2;

    const STEPS_PER_FRAME = 5;

    const sphereGeometry = new THREE.IcosahedronGeometry( SPHERE_RADIUS, 5 );
    const sphereMaterial = new THREE.MeshLambertMaterial( { color: 0xbbbb44 } );

    const spheres = [];
    let sphereIdx = 0;

    for ( let i = 0; i < NUM_SPHERES; i ++ ) {

        const sphere = new THREE.Mesh( sphereGeometry, sphereMaterial );
        sphere.castShadow = true;
        sphere.receiveShadow = true;

        scene.add( sphere );

        spheres.push( {
            mesh: sphere,
            collider: new THREE.Sphere( new THREE.Vector3( 0, - 100, 0 ), SPHERE_RADIUS ),
            velocity: new THREE.Vector3()
        } );

    }

    const worldOctree = new Octree();

    const playerCollider = new Capsule( new THREE.Vector3( 0, 0.35, 0 ), new THREE.Vector3( 0, 1, 0 ), 0.35 );

    const playerVelocity = new THREE.Vector3();
    const playerDirection = new THREE.Vector3();

    let playerOnFloor = false;
    let mouseTime = 0;

    const keyStates = {};

    const vector1 = new THREE.Vector3();
    const vector2 = new THREE.Vector3();
    const vector3 = new THREE.Vector3();

    document.addEventListener( 'keydown', ( event ) => {

        keyStates[ event.code ] = true;

    } );

    document.addEventListener( 'keyup', ( event ) => {

        keyStates[ event.code ] = false;

    } );

    container.addEventListener( 'mousedown', () => {

        document.body.requestPointerLock();

        mouseTime = performance.now();

    } );

    document.addEventListener( 'mouseup', () => {

        if ( document.pointerLockElement !== null ) throwBall();

    } );

    document.body.addEventListener( 'mousemove', ( event ) => {

        if ( document.pointerLockElement === document.body ) {

            camera.rotation.y -= event.movementX / 500;
            camera.rotation.x -= event.movementY / 500;

        }

    } );

    window.addEventListener( 'resize', onWindowResize );

    function onWindowResize() {

        camera.aspect = window.innerWidth / window.innerHeight;
        camera.updateProjectionMatrix();

        renderer.setSize( window.innerWidth, window.innerHeight );

    }

    function throwBall() {

        const sphere = spheres[ sphereIdx ];

        camera.getWorldDirection( playerDirection );

        sphere.collider.center.copy( playerCollider.end ).addScaledVector( playerDirection, playerCollider.radius * 1.5 );

        // throw the ball with more force if we hold the button longer, and if we move forward

        const impulse = 15 + 30 * ( 1 - Math.exp( ( mouseTime - performance.now() ) * 0.001 ) );

        sphere.velocity.copy( playerDirection ).multiplyScalar( impulse );
        sphere.velocity.addScaledVector( playerVelocity, 2 );

        sphereIdx = ( sphereIdx + 1 ) % spheres.length;

    }

    function playerCollisions() {

        const result = worldOctree.capsuleIntersect( playerCollider );

        playerOnFloor = false;

        if ( result ) {

            playerOnFloor = result.normal.y > 0;

            if ( ! playerOnFloor ) {

                playerVelocity.addScaledVector( result.normal, - result.normal.dot( playerVelocity ) );

            }

            playerCollider.translate( result.normal.multiplyScalar( result.depth ) );

        }

    }

    function updatePlayer( deltaTime ) {

        let damping = Math.exp( - 4 * deltaTime ) - 1;

        if ( ! playerOnFloor ) {

            playerVelocity.y -= GRAVITY * deltaTime;

            // small air resistance
            damping *= 0.1;

        }

        playerVelocity.addScaledVector( playerVelocity, damping );

        const deltaPosition = playerVelocity.clone().multiplyScalar( deltaTime );
        playerCollider.translate( deltaPosition );

        playerCollisions();

        camera.position.copy( playerCollider.end );

    }

    function playerSphereCollision( sphere ) {

        const center = vector1.addVectors( playerCollider.start, playerCollider.end ).multiplyScalar( 0.5 );

        const sphere_center = sphere.collider.center;

        const r = playerCollider.radius + sphere.collider.radius;
        const r2 = r * r;

        // approximation: player = 3 spheres

        for ( const point of [ playerCollider.start, playerCollider.end, center ] ) {

            const d2 = point.distanceToSquared( sphere_center );

            if ( d2 < r2 ) {

                const normal = vector1.subVectors( point, sphere_center ).normalize();
                const v1 = vector2.copy( normal ).multiplyScalar( normal.dot( playerVelocity ) );
                const v2 = vector3.copy( normal ).multiplyScalar( normal.dot( sphere.velocity ) );

                playerVelocity.add( v2 ).sub( v1 );
                sphere.velocity.add( v1 ).sub( v2 );

                const d = ( r - Math.sqrt( d2 ) ) / 2;
                sphere_center.addScaledVector( normal, - d );

            }

        }

    }

    function spheresCollisions() {

        for ( let i = 0, length = spheres.length; i < length; i ++ ) {

            const s1 = spheres[ i ];

            for ( let j = i + 1; j < length; j ++ ) {

                const s2 = spheres[ j ];

                const d2 = s1.collider.center.distanceToSquared( s2.collider.center );
                const r = s1.collider.radius + s2.collider.radius;
                const r2 = r * r;

                if ( d2 < r2 ) {

                    const normal = vector1.subVectors( s1.collider.center, s2.collider.center ).normalize();
                    const v1 = vector2.copy( normal ).multiplyScalar( normal.dot( s1.velocity ) );
                    const v2 = vector3.copy( normal ).multiplyScalar( normal.dot( s2.velocity ) );

                    s1.velocity.add( v2 ).sub( v1 );
                    s2.velocity.add( v1 ).sub( v2 );

                    const d = ( r - Math.sqrt( d2 ) ) / 2;

                    s1.collider.center.addScaledVector( normal, d );
                    s2.collider.center.addScaledVector( normal, - d );

                }

            }

        }

    }

    function updateSpheres( deltaTime ) {

        spheres.forEach( sphere => {

            sphere.collider.center.addScaledVector( sphere.velocity, deltaTime );

            const result = worldOctree.sphereIntersect( sphere.collider );

            if ( result ) {

                sphere.velocity.addScaledVector( result.normal, - result.normal.dot( sphere.velocity ) * 1.5 );
                sphere.collider.center.add( result.normal.multiplyScalar( result.depth ) );

            } else {

                sphere.velocity.y -= GRAVITY * deltaTime;

            }

            const damping = Math.exp( - 1.5 * deltaTime ) - 1;
            sphere.velocity.addScaledVector( sphere.velocity, damping );

            playerSphereCollision( sphere );

        } );

        spheresCollisions();

        for ( const sphere of spheres ) {

            sphere.mesh.position.copy( sphere.collider.center );

        }

    }

    function getForwardVector() {

        camera.getWorldDirection( playerDirection );
        playerDirection.y = 0;
        playerDirection.normalize();

        return playerDirection;

    }

    function getSideVector() {

        camera.getWorldDirection( playerDirection );
        playerDirection.y = 0;
        playerDirection.normalize();
        playerDirection.cross( camera.up );

        return playerDirection;

    }

    function controls( deltaTime ) {

        // gives a bit of air control
        const speedDelta = deltaTime * ( playerOnFloor ? 25 : 8 );

        if ( keyStates[ 'KeyW' ] ) {

            playerVelocity.add( getForwardVector().multiplyScalar( speedDelta ) );

        }

        if ( keyStates[ 'KeyS' ] ) {

            playerVelocity.add( getForwardVector().multiplyScalar( - speedDelta ) );

        }

        if ( keyStates[ 'KeyA' ] ) {

            playerVelocity.add( getSideVector().multiplyScalar( - speedDelta ) );

        }

        if ( keyStates[ 'KeyD' ] ) {

            playerVelocity.add( getSideVector().multiplyScalar( speedDelta ) );

        }

        if ( playerOnFloor ) {

            if ( keyStates[ 'Space' ] ) {

                playerVelocity.y = 15;

            }

        }

    }

    const loader = new GLTFLoader().setPath( './models/gltf/' );

    loader.load( 'collision-world.glb', ( gltf ) => {

        scene.add( gltf.scene );

        worldOctree.fromGraphNode( gltf.scene );

        gltf.scene.traverse( child => {

            if ( child.isMesh ) {

                child.castShadow = true;
                child.receiveShadow = true;

                if ( child.material.map ) {

                    child.material.map.anisotropy = 4;

                }

            }

        } );

        const helper = new OctreeHelper( worldOctree );
        helper.visible = false;
        scene.add( helper );

        const gui = new GUI( { width: 200 } );
        gui.add( { debug: false }, 'debug' )
            .onChange( function ( value ) {

                helper.visible = value;

            } );

        animate();

    } );

    function teleportPlayerIfOob() {

        if ( camera.position.y <= - 25 ) {

            playerCollider.start.set( 0, 0.35, 0 );
            playerCollider.end.set( 0, 1, 0 );
            playerCollider.radius = 0.35;
            camera.position.copy( playerCollider.end );
            camera.rotation.set( 0, 0, 0 );

        }

    }


    function animate() {

        const deltaTime = Math.min( 0.05, clock.getDelta() ) / STEPS_PER_FRAME;

        // we look for collisions in substeps to mitigate the risk of
        // an object traversing another too quickly for detection.

        for ( let i = 0; i < STEPS_PER_FRAME; i ++ ) {

            controls( deltaTime );

            updatePlayer( deltaTime );

            updateSpheres( deltaTime );

            teleportPlayerIfOob();

        }

        renderer.render( scene, camera );

        stats.update();

        requestAnimationFrame( animate );

    }

</script>
</body>
</html>
